260 U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



hairy around the naked tubercles, and the hairs on the ears longer than in the preceding 

 (summer?) specimens. Killed December 3, 1852. Head, 3 inches; head and body, 11 ; tail 

 vertebra, 9 ; tail vertebrae, with hairs, 11. (No. 178, Detroit, Michigan.) 



6th. Similar to the last, but tail distinctly annulated with brown. Soles more hairy. The 

 hairs of the convexity of the ear still longer. (Winter, No. 720, Cook county, Illinois.) 



7th. Colors above lighter, like a rather dusky gray squirrel. Hairs on the under surface of 

 body with more brownish rusty ; less black. Tail hairs annulated distinctly ; their tips whitish 

 or rusty gray. Soles more naked. Hair on the ears shorter. (Spring, No. 721, Cook county, 

 Illinois.) 



8th. General character that of a gray squirrel. Nose, inside of thighs, and region around 

 genitalia dusky. Hairs annulated. Under surface, from chin to thighs, brownish rusty. 

 The hairs annulated or tipped with blackish ; a narrow streak on each side the median line of 

 the belly grayish white. Tail as in gray squirrels. Soles naked. (July, 1853, $ , No. 256, 

 Kacine ; 257 similar.) 



9th. Similar to the last, but with no dusky on the inside of the thighs. Hairs of under 

 surfaces only annulated on the throat and neck, where they are tinged with gamboge yellow. 

 (No. 970, West Northfield, Illinois.) Another specimen with the light stripes on the belly 

 larger, purer white, and confluent in places. The region around the teats is, however, more 

 dusky than elsewhere. (No. 1136, Fort des Moines, Iowa.) 



10th. Chin and inside of the fore legs suffused with brownish ; an indistinct stripe of pale 

 brown on each side of the median line of the belly. No annulation of inferior hairs. (No. 

 1672, Carlisle, Pa.) 



llth. The next stage is the regular gray squirrel, in which the prevailing color of the hairs 

 above is gray, with subterminal annulations of black, more or less concealed by the gray tips. 

 The entire under parts are white ; the sides of the white with a narrow margin on the flanks of 

 yellowish rusty. This color also overlays the gray of the upper parts in varying proportions, 

 sometimes confined to the head ; sometimes along the middle of the back as a narrow stripe ; 

 sometimes as a broader one ; sometimes forming a cross across the shoulders ; sometimes forming 

 a uniform wash over the whole surface. The proportion of yellow also varies considerably. 



The ears are generally of a yellowish brown color, rather lighter at the posterior surface. 

 In summer, the hair is everywhere very short, and uniform in length. With the approach of 

 cold weather, it lengthens on the convex postero-internal surface of the ear, except along a 

 narrow anterior margin. A similar lengthening takes place in a small patch on the neck at 

 the base of the ear behind. These lengthened hairs, being white and woolly in appearance, 

 form a conspicuous mark, not nearly so appreciable, if at all, in summer. The extreme border 

 of the ear, however, (about one-tenth to one-twentieth of an inch wide,) remains short-haired, 

 and of a rusty yellow color, strongly contrasted against the woolly white. 



Coincident with this change of hair on the ears is a similar one on the soles. In summer 

 these are entirely free from hair, except for about half an inch from the extreme heel, which is 

 densely furred. The naked space commences in a transverse line about as far behind the pos 

 terior tubercle as its own length. With the approach of cold weather, hairs begin to grow on 

 the soles until, in midwinter, they are completely covered with close, short hairs, except on the 

 five large tubercles and the balls of the toes, and perhaps a short distance behind them. In 

 many cases, too, a similar development of hairs takes place between the tubercles of the palms. 

 Although in more northern specimens the amount of growth of fur on the ears and soles is 



